Construction Of Zinc Metal Anode Based On Copper Mesh And Electrochemical Properties

Aqueous zinc-ion batteries have the essential advantages of non-toxic and safe,environmentally friendly and inexpensive,becoming a very competitive new battery system.Among them,zinc metal has low equilibrium potential,high hydrogen evolution overpotential.It can also be efficiently and reversible deposition/peel in aqueous electrolyte,becoming the most widely used anode material in this system.However,the zinc anode is plagued by the following problems during the plating and striping process:（1）Because of the uneven distribution of the electric field in the battery and the"tip effect",the Zn²⁺deposition is uneven,and it is easy to grow into dendrites.On the one hand,the shedding dendrites form"dead zinc"to lose the active electrode substance.On the other hand,severe dendrite growth will puncture the diaphragm and induce battery short-circuit failure.（2）There is a reduction competition between H⁺and Zn²⁺in the electrochemical process,and the resulting H₂ will cause the battery to bulge to flatulence,which is a potential safety hazard.（3）The highly active zinc has a self-corrosion phenomenon in the electrolyte,increasing local OH^-concentration at the negative electrode interface,and then reacts with Zn²⁺to form a poorly soluble Zn₄（SO₄）OH₆·n H₂O passivation layer on the electrode surface,which increases the polarization and resistance of the electrode and intensifies the growth of zinc dendrites.In order to overcome these problems,this paper constructed a dendritic-free zinc metal anode based on the copper mesh from the structural design and then realized a stable long-cycle zinc-ion battery.The specific research content is as follows:Firstly,we grew a layer of Cu₂O nanoparticles on the surface of the copper mesh as the current collector of the zinc anode by hydrothermal and annealing methods and explored the deposition behavior of Zn on this current collector.The copper mesh modified by Cu₂O nanoparticles significantly improves the electrolyte’s wettability,which helps to form a uniform zinc ion flow at the interface and ensures the efficient transport of Zn²⁺.In addition,Cu₂O was reduced to Cu elemental with high affinity with zinc at the beginning of the electrochemical deposition,providing a large number of Zn nucleation sites,effectively guiding the uniform deposition of Zn²⁺,and realizing dendrite-free zinc anodes,at a current density of 1 m A cm^-2,it can be stable for 700hours.The current collector pre-deposited zinc was used as the negative electrode to assemble the whole battery to explore its application prospect.Secondly,we also used electrochemical deposition to simultaneously deposit metals Zn and In on the copper mesh as the anode of zinc-ion batteries.By adjusting the electrolyte concentration to obtain the optimal ratio of Zn and In,and then exploring the spillover of the introduction of In on the electrochemical behavior and performance of zinc anode.It was found that the introduction of In significantly improved the problems of hydrogen evolution and side reaction,and at the same time promoted the uniform deposition of Zn²⁺and prevented the growth of zinc dendrites.Based on the above advantages,the introduction of In effectively prolongs the cycle life of the metal anode.At the condition of 10 m A cm^-2 and 2 m Ah cm^-2,an overpotential of less than0.1 V can be maintained and the cycle can be stable for 500 hours.